/* Students.AIO developer website — single stylesheet, no build step. */

:root {
  --indigo: #4f46e5;
  --indigo-dark: #4338ca;
  --purple: #7c3aed;
  --violet: #8b5cf6;
  --ink: #0f172a;
  --body: #475569;
  --muted: #64748b;
  --line: #e2e8f0;
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --gradient: linear-gradient(135deg, #4f46e5 0%, #7c3aed 55%, #a855f7 100%);
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, .06), 0 1px 3px rgba(15, 23, 42, .08);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, .07), 0 12px 28px rgba(79, 70, 229, .09);
  --shadow-lg: 0 18px 48px rgba(79, 70, 229, .16);
  --radius: 18px;
  --radius-sm: 12px;
  --maxw: 1120px;
  --font: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--body);
  background: var(--bg);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { color: var(--ink); line-height: 1.2; margin: 0 0 .5em; font-weight: 700; letter-spacing: -.02em; }
h1 { font-size: clamp(2.1rem, 5.2vw, 3.5rem); font-weight: 800; }
h2 { font-size: clamp(1.6rem, 3.4vw, 2.35rem); }
h3 { font-size: 1.15rem; }
p { margin: 0 0 1rem; }
a { color: var(--indigo); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; display: block; }

.wrap { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

.skip {
  position: absolute; left: -9999px; top: 0; background: var(--ink); color: #fff;
  padding: 12px 18px; z-index: 100; border-radius: 0 0 var(--radius-sm) 0;
}
.skip:focus { left: 0; }

:focus-visible { outline: 3px solid var(--violet); outline-offset: 3px; border-radius: 6px; }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255, 255, 255, .82);
  backdrop-filter: saturate(180%) blur(18px);
  -webkit-backdrop-filter: saturate(180%) blur(18px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; justify-content: space-between; gap: 18px; height: 68px; }
.brand { display: flex; align-items: center; gap: 11px; font-weight: 800; color: var(--ink); font-size: 1.12rem; letter-spacing: -.02em; }
.brand:hover { text-decoration: none; }
.brand-mark {
  width: 36px; height: 36px; border-radius: 50%; object-fit: cover;
  display: block; flex-shrink: 0; background: #fff;
  box-shadow: 0 4px 12px rgba(79, 70, 229, .32);
}
.nav-links { display: flex; align-items: center; gap: 4px; list-style: none; margin: 0; padding: 0; }
.nav-links a {
  color: var(--body); font-size: .93rem; font-weight: 500; padding: 8px 14px;
  border-radius: 9px; transition: background .18s ease, color .18s ease;
}
.nav-links a:hover { background: var(--bg-soft); color: var(--ink); text-decoration: none; }
.nav-links a[aria-current="page"] { color: var(--indigo); background: #eef2ff; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 9px;
  padding: 13px 26px; border-radius: 999px; font-weight: 600; font-size: .95rem;
  font-family: inherit; cursor: pointer; border: 1px solid transparent;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-2px); }
.btn-primary { background: var(--gradient); color: #fff; box-shadow: 0 8px 22px rgba(79, 70, 229, .34); }
.btn-primary:hover { box-shadow: 0 14px 30px rgba(79, 70, 229, .42); }
.btn-ghost { background: #fff; color: var(--ink); border-color: var(--line); box-shadow: var(--shadow-sm); }
.btn-ghost:hover { border-color: #cbd5e1; }

/* ---------- Hero ---------- */
.hero { position: relative; overflow: hidden; padding: clamp(64px, 9vw, 112px) 0 clamp(56px, 8vw, 96px); text-align: center; }
.hero::before {
  content: ""; position: absolute; inset: -40% 0 auto 0; height: 140%;
  background:
    radial-gradient(48% 46% at 22% 18%, rgba(79, 70, 229, .17), transparent 62%),
    radial-gradient(44% 44% at 78% 12%, rgba(168, 85, 247, .16), transparent 60%);
  z-index: -1;
}
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  background: #eef2ff; color: var(--indigo-dark); border: 1px solid #e0e7ff;
  padding: 7px 16px; border-radius: 999px; font-size: .8rem; font-weight: 600;
  letter-spacing: .04em; text-transform: uppercase; margin-bottom: 22px;
}
.tagline {
  font-size: clamp(1.05rem, 2.4vw, 1.35rem); font-weight: 600;
  background: var(--gradient); -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: var(--indigo);
  letter-spacing: .01em; margin: 0 0 14px;
}
.lede { font-size: clamp(1rem, 2.1vw, 1.16rem); color: var(--body); max-width: 640px; margin: 0 auto 32px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 13px; justify-content: center; }

/* ---------- Sections ---------- */
section { padding: clamp(56px, 8vw, 92px) 0; }
.section-soft { background: var(--bg-soft); border-block: 1px solid var(--line); }
.section-head { max-width: 660px; margin: 0 auto clamp(34px, 5vw, 54px); text-align: center; }
.section-head p { color: var(--muted); font-size: 1.03rem; margin: 0; }

.grid { display: grid; gap: 22px; grid-template-columns: repeat(auto-fit, minmax(272px, 1fr)); }

.card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 30px 26px; box-shadow: var(--shadow-sm);
  transition: transform .22s ease, box-shadow .22s ease, border-color .22s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: #dbe2f0; }
.card h3 { margin-bottom: .4rem; }
.card p { margin: 0; font-size: .94rem; color: var(--muted); }
.icon {
  width: 46px; height: 46px; border-radius: 13px; display: grid; place-items: center;
  background: #eef2ff; color: var(--indigo); font-size: 1.3rem; margin-bottom: 16px;
}

/* ---------- Prose (legal pages) ---------- */
.prose { max-width: 820px; margin: 0 auto; }
.prose h2 { font-size: 1.32rem; margin-top: 2.4rem; }
.prose h2:first-of-type { margin-top: 0; }
.prose h3 { font-size: 1.02rem; margin-top: 1.6rem; color: var(--indigo-dark); }
.prose ul { padding-left: 20px; margin: 0 0 1.15rem; }
.prose li { margin-bottom: .45rem; }
.prose strong { color: var(--ink); }
.prose table { width: 100%; border-collapse: collapse; margin: 0 0 1.3rem; font-size: .92rem; }
.prose th, .prose td { border: 1px solid var(--line); padding: 11px 14px; text-align: left; vertical-align: top; }
.prose th { background: var(--bg-soft); color: var(--ink); font-weight: 600; }
.note {
  background: #eef2ff; border: 1px solid #e0e7ff; border-left: 4px solid var(--indigo);
  border-radius: var(--radius-sm); padding: 16px 20px; margin: 0 0 1.5rem; font-size: .93rem;
}
.note p:last-child { margin: 0; }
.updated { color: var(--muted); font-size: .9rem; margin-bottom: 2rem; }

/* ---------- Page hero (inner pages) ---------- */
.page-hero { padding: clamp(48px, 7vw, 78px) 0 clamp(28px, 4vw, 40px); text-align: center; }
.page-hero p { max-width: 620px; margin: 0 auto; color: var(--muted); font-size: 1.04rem; }

/* ---------- Contact ---------- */
.contact-grid { display: grid; gap: 22px; grid-template-columns: repeat(auto-fit, minmax(268px, 1fr)); }
.contact-card { text-align: center; }
.contact-card a { font-weight: 600; word-break: break-word; }

/* ---------- Footer ---------- */
.site-footer { background: var(--ink); color: #94a3b8; padding: 54px 0 30px; font-size: .92rem; }
.footer-top { display: grid; gap: 34px; grid-template-columns: 1.6fr 1fr 1fr; margin-bottom: 36px; }
.site-footer .brand { color: #fff; margin-bottom: 14px; }
.site-footer p { color: #94a3b8; margin: 0; max-width: 340px; }
.footer-col h4 { color: #fff; font-size: .82rem; text-transform: uppercase; letter-spacing: .09em; margin-bottom: 14px; }
.footer-col ul { list-style: none; margin: 0; padding: 0; }
.footer-col li { margin-bottom: 9px; }
.footer-col a { color: #94a3b8; }
.footer-col a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid #1e293b; padding-top: 22px;
  display: flex; flex-wrap: wrap; gap: 10px; justify-content: space-between; align-items: center;
}
.footer-bottom p { max-width: none; }

/* ---------- Motion ---------- */
@media (prefers-reduced-motion: no-preference) {
  .fade-up { opacity: 0; transform: translateY(16px); animation: fadeUp .6s cubic-bezier(.22, 1, .36, 1) forwards; }
  .fade-up:nth-child(2) { animation-delay: .07s; }
  .fade-up:nth-child(3) { animation-delay: .14s; }
  .fade-up:nth-child(4) { animation-delay: .21s; }
  .fade-up:nth-child(5) { animation-delay: .28s; }
  .fade-up:nth-child(6) { animation-delay: .35s; }
  @keyframes fadeUp { to { opacity: 1; transform: none; } }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn:hover, .card:hover { transform: none; }
}

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  .footer-top { grid-template-columns: 1fr 1fr; }
  .footer-top > div:first-child { grid-column: 1 / -1; }
}
@media (max-width: 720px) {
  .nav { height: auto; padding: 12px 0; flex-wrap: wrap; }
  .nav-links { width: 100%; overflow-x: auto; justify-content: flex-start; padding-bottom: 4px; }
  .nav-links a { padding: 7px 11px; font-size: .89rem; white-space: nowrap; }
  .hero-actions .btn { width: 100%; }
}
@media (max-width: 520px) {
  .footer-top { grid-template-columns: 1fr; }
  .card { padding: 26px 22px; }
}